diff options
Diffstat (limited to 'vendor/github.com/Microsoft/go-winio/backuptar/tar.go')
| -rw-r--r-- | vendor/github.com/Microsoft/go-winio/backuptar/tar.go | 439 |
1 files changed, 439 insertions, 0 deletions
diff --git a/vendor/github.com/Microsoft/go-winio/backuptar/tar.go b/vendor/github.com/Microsoft/go-winio/backuptar/tar.go new file mode 100644 index 000000000..53da908f1 --- /dev/null +++ b/vendor/github.com/Microsoft/go-winio/backuptar/tar.go @@ -0,0 +1,439 @@ +// +build windows + +package backuptar + +import ( + "encoding/base64" + "errors" + "fmt" + "io" + "io/ioutil" + "path/filepath" + "strconv" + "strings" + "syscall" + "time" + + "github.com/Microsoft/go-winio" + "github.com/Microsoft/go-winio/archive/tar" // until archive/tar supports pax extensions in its interface +) + +const ( + c_ISUID = 04000 // Set uid + c_ISGID = 02000 // Set gid + c_ISVTX = 01000 // Save text (sticky bit) + c_ISDIR = 040000 // Directory + c_ISFIFO = 010000 // FIFO + c_ISREG = 0100000 // Regular file + c_ISLNK = 0120000 // Symbolic link + c_ISBLK = 060000 // Block special file + c_ISCHR = 020000 // Character special file + c_ISSOCK = 0140000 // Socket +) + +const ( + hdrFileAttributes = "fileattr" + hdrSecurityDescriptor = "sd" + hdrRawSecurityDescriptor = "rawsd" + hdrMountPoint = "mountpoint" + hdrEaPrefix = "xattr." +) + +func writeZeroes(w io.Writer, count int64) error { + buf := make([]byte, 8192) + c := len(buf) + for i := int64(0); i < count; i += int64(c) { + if int64(c) > count-i { + c = int(count - i) + } + _, err := w.Write(buf[:c]) + if err != nil { + return err + } + } + return nil +} + +func copySparse(t *tar.Writer, br *winio.BackupStreamReader) error { + curOffset := int64(0) + for { + bhdr, err := br.Next() + if err == io.EOF { + err = io.ErrUnexpectedEOF + } + if err != nil { + return err + } + if bhdr.Id != winio.BackupSparseBlock { + return fmt.Errorf("unexpected stream %d", bhdr.Id) + } + + // archive/tar does not support writing sparse files + // so just write zeroes to catch up to the current offset. + err = writeZeroes(t, bhdr.Offset-curOffset) + if bhdr.Size == 0 { + break + } + n, err := io.Copy(t, br) + if err != nil { + return err + } + curOffset = bhdr.Offset + n + } + return nil +} + +// BasicInfoHeader creates a tar header from basic file information. +func BasicInfoHeader(name string, size int64, fileInfo *winio.FileBasicInfo) *tar.Header { + hdr := &tar.Header{ + Name: filepath.ToSlash(name), + Size: size, + Typeflag: tar.TypeReg, + ModTime: time.Unix(0, fileInfo.LastWriteTime.Nanoseconds()), + ChangeTime: time.Unix(0, fileInfo.ChangeTime.Nanoseconds()), + AccessTime: time.Unix(0, fileInfo.LastAccessTime.Nanoseconds()), + CreationTime: time.Unix(0, fileInfo.CreationTime.Nanoseconds()), + Winheaders: make(map[string]string), + } + hdr.Winheaders[hdrFileAttributes] = fmt.Sprintf("%d", fileInfo.FileAttributes) + + if (fileInfo.FileAttributes & syscall.FILE_ATTRIBUTE_DIRECTORY) != 0 { + hdr.Mode |= c_ISDIR + hdr.Size = 0 + hdr.Typeflag = tar.TypeDir + } + return hdr +} + +// WriteTarFileFromBackupStream writes a file to a tar writer using data from a Win32 backup stream. +// +// This encodes Win32 metadata as tar pax vendor extensions starting with MSWINDOWS. +// +// The additional Win32 metadata is: +// +// MSWINDOWS.fileattr: The Win32 file attributes, as a decimal value +// +// MSWINDOWS.rawsd: The Win32 security descriptor, in raw binary format +// +// MSWINDOWS.mountpoint: If present, this is a mount point and not a symlink, even though the type is '2' (symlink) +func WriteTarFileFromBackupStream(t *tar.Writer, r io.Reader, name string, size int64, fileInfo *winio.FileBasicInfo) error { + name = filepath.ToSlash(name) + hdr := BasicInfoHeader(name, size, fileInfo) + + // If r can be seeked, then this function is two-pass: pass 1 collects the + // tar header data, and pass 2 copies the data stream. If r cannot be + // seeked, then some header data (in particular EAs) will be silently lost. + var ( + restartPos int64 + err error + ) + sr, readTwice := r.(io.Seeker) + if readTwice { + if restartPos, err = sr.Seek(0, io.SeekCurrent); err != nil { + readTwice = false + } + } + + br := winio.NewBackupStreamReader(r) + var dataHdr *winio.BackupHeader + for dataHdr == nil { + bhdr, err := br.Next() + if err == io.EOF { + break + } + if err != nil { + return err + } + switch bhdr.Id { + case winio.BackupData: + hdr.Mode |= c_ISREG + if !readTwice { + dataHdr = bhdr + } + case winio.BackupSecurity: + sd, err := ioutil.ReadAll(br) + if err != nil { + return err + } + hdr.Winheaders[hdrRawSecurityDescriptor] = base64.StdEncoding.EncodeToString(sd) + + case winio.BackupReparseData: + hdr.Mode |= c_ISLNK + hdr.Typeflag = tar.TypeSymlink + reparseBuffer, err := ioutil.ReadAll(br) + rp, err := winio.DecodeReparsePoint(reparseBuffer) + if err != nil { + return err + } + if rp.IsMountPoint { + hdr.Winheaders[hdrMountPoint] = "1" + } + hdr.Linkname = rp.Target + + case winio.BackupEaData: + eab, err := ioutil.ReadAll(br) + if err != nil { + return err + } + eas, err := winio.DecodeExtendedAttributes(eab) + if err != nil { + return err + } + for _, ea := range eas { + // Use base64 encoding for the binary value. Note that there + // is no way to encode the EA's flags, since their use doesn't + // make any sense for persisted EAs. + hdr.Winheaders[hdrEaPrefix+ea.Name] = base64.StdEncoding.EncodeToString(ea.Value) + } + + case winio.BackupAlternateData, winio.BackupLink, winio.BackupPropertyData, winio.BackupObjectId, winio.BackupTxfsData: + // ignore these streams + default: + return fmt.Errorf("%s: unknown stream ID %d", name, bhdr.Id) + } + } + + err = t.WriteHeader(hdr) + if err != nil { + return err + } + + if readTwice { + // Get back to the data stream. + if _, err = sr.Seek(restartPos, io.SeekStart); err != nil { + return err + } + for dataHdr == nil { + bhdr, err := br.Next() + if err == io.EOF { + break + } + if err != nil { + return err + } + if bhdr.Id == winio.BackupData { + dataHdr = bhdr + } + } + } + + if dataHdr != nil { + // A data stream was found. Copy the data. + if (dataHdr.Attributes & winio.StreamSparseAttributes) == 0 { + if size != dataHdr.Size { + return fmt.Errorf("%s: mismatch between file size %d and header size %d", name, size, dataHdr.Size) + } + _, err = io.Copy(t, br) + if err != nil { + return err + } + } else { + err = copySparse(t, br) + if err != nil { + return err + } + } + } + + // Look for streams after the data stream. The only ones we handle are alternate data streams. + // Other streams may have metadata that could be serialized, but the tar header has already + // been written. In practice, this means that we don't get EA or TXF metadata. + for { + bhdr, err := br.Next() + if err == io.EOF { + break + } + if err != nil { + return err + } + switch bhdr.Id { + case winio.BackupAlternateData: + altName := bhdr.Name + if strings.HasSuffix(altName, ":$DATA") { + altName = altName[:len(altName)-len(":$DATA")] + } + if (bhdr.Attributes & winio.StreamSparseAttributes) == 0 { + hdr = &tar.Header{ + Name: name + altName, + Mode: hdr.Mode, + Typeflag: tar.TypeReg, + Size: bhdr.Size, + ModTime: hdr.ModTime, + AccessTime: hdr.AccessTime, + ChangeTime: hdr.ChangeTime, + } + err = t.WriteHeader(hdr) + if err != nil { + return err + } + _, err = io.Copy(t, br) + if err != nil { + return err + } + + } else { + // Unsupported for now, since the size of the alternate stream is not present + // in the backup stream until after the data has been read. + return errors.New("tar of sparse alternate data streams is unsupported") + } + case winio.BackupEaData, winio.BackupLink, winio.BackupPropertyData, winio.BackupObjectId, winio.BackupTxfsData: + // ignore these streams + default: + return fmt.Errorf("%s: unknown stream ID %d after data", name, bhdr.Id) + } + } + return nil +} + +// FileInfoFromHeader retrieves basic Win32 file information from a tar header, using the additional metadata written by +// WriteTarFileFromBackupStream. +func FileInfoFromHeader(hdr *tar.Header) (name string, size int64, fileInfo *winio.FileBasicInfo, err error) { + name = hdr.Name + if hdr.Typeflag == tar.TypeReg || hdr.Typeflag == tar.TypeRegA { + size = hdr.Size + } + fileInfo = &winio.FileBasicInfo{ + LastAccessTime: syscall.NsecToFiletime(hdr.AccessTime.UnixNano()), + LastWriteTime: syscall.NsecToFiletime(hdr.ModTime.UnixNano()), + ChangeTime: syscall.NsecToFiletime(hdr.ChangeTime.UnixNano()), + CreationTime: syscall.NsecToFiletime(hdr.CreationTime.UnixNano()), + } + if attrStr, ok := hdr.Winheaders[hdrFileAttributes]; ok { + attr, err := strconv.ParseUint(attrStr, 10, 32) + if err != nil { + return "", 0, nil, err + } + fileInfo.FileAttributes = uintptr(attr) + } else { + if hdr.Typeflag == tar.TypeDir { + fileInfo.FileAttributes |= syscall.FILE_ATTRIBUTE_DIRECTORY + } + } + return +} + +// WriteBackupStreamFromTarFile writes a Win32 backup stream from the current tar file. Since this function may process multiple +// tar file entries in order to collect all the alternate data streams for the file, it returns the next +// tar file that was not processed, or io.EOF is there are no more. +func WriteBackupStreamFromTarFile(w io.Writer, t *tar.Reader, hdr *tar.Header) (*tar.Header, error) { + bw := winio.NewBackupStreamWriter(w) + var sd []byte + var err error + // Maintaining old SDDL-based behavior for backward compatibility. All new tar headers written + // by this library will have raw binary for the security descriptor. + if sddl, ok := hdr.Winheaders[hdrSecurityDescriptor]; ok { + sd, err = winio.SddlToSecurityDescriptor(sddl) + if err != nil { + return nil, err + } + } + if sdraw, ok := hdr.Winheaders[hdrRawSecurityDescriptor]; ok { + sd, err = base64.StdEncoding.DecodeString(sdraw) + if err != nil { + return nil, err + } + } + if len(sd) != 0 { + bhdr := winio.BackupHeader{ + Id: winio.BackupSecurity, + Size: int64(len(sd)), + } + err := bw.WriteHeader(&bhdr) + if err != nil { + return nil, err + } + _, err = bw.Write(sd) + if err != nil { + return nil, err + } + } + var eas []winio.ExtendedAttribute + for k, v := range hdr.Winheaders { + if !strings.HasPrefix(k, hdrEaPrefix) { + continue + } + data, err := base64.StdEncoding.DecodeString(v) + if err != nil { + return nil, err + } + eas = append(eas, winio.ExtendedAttribute{ + Name: k[len(hdrEaPrefix):], + Value: data, + }) + } + if len(eas) != 0 { + eadata, err := winio.EncodeExtendedAttributes(eas) + if err != nil { + return nil, err + } + bhdr := winio.BackupHeader{ + Id: winio.BackupEaData, + Size: int64(len(eadata)), + } + err = bw.WriteHeader(&bhdr) + if err != nil { + return nil, err + } + _, err = bw.Write(eadata) + if err != nil { + return nil, err + } + } + if hdr.Typeflag == tar.TypeSymlink { + _, isMountPoint := hdr.Winheaders[hdrMountPoint] + rp := winio.ReparsePoint{ + Target: filepath.FromSlash(hdr.Linkname), + IsMountPoint: isMountPoint, + } + reparse := winio.EncodeReparsePoint(&rp) + bhdr := winio.BackupHeader{ + Id: winio.BackupReparseData, + Size: int64(len(reparse)), + } + err := bw.WriteHeader(&bhdr) + if err != nil { + return nil, err + } + _, err = bw.Write(reparse) + if err != nil { + return nil, err + } + } + if hdr.Typeflag == tar.TypeReg || hdr.Typeflag == tar.TypeRegA { + bhdr := winio.BackupHeader{ + Id: winio.BackupData, + Size: hdr.Size, + } + err := bw.WriteHeader(&bhdr) + if err != nil { + return nil, err + } + _, err = io.Copy(bw, t) + if err != nil { + return nil, err + } + } + // Copy all the alternate data streams and return the next non-ADS header. + for { + ahdr, err := t.Next() + if err != nil { + return nil, err + } + if ahdr.Typeflag != tar.TypeReg || !strings.HasPrefix(ahdr.Name, hdr.Name+":") { + return ahdr, nil + } + bhdr := winio.BackupHeader{ + Id: winio.BackupAlternateData, + Size: ahdr.Size, + Name: ahdr.Name[len(hdr.Name):] + ":$DATA", + } + err = bw.WriteHeader(&bhdr) + if err != nil { + return nil, err + } + _, err = io.Copy(bw, t) + if err != nil { + return nil, err + } + } +} |